class_docstr: A helper class that represents input string that to be modified.
  
  Text that Sample contains parsed in data set,
  ``TextField`` provides multiple methods for Sample to modify.
  
  Support sentence level and word level modification,
  default using word level API.
docstr: Get NER tags.
  
  Example::
  
      given sentence 'Lionel Messi is a football player from Argentina.'
  
      >>[('Lionel Messi', 0, 2, 'PERSON'),
         ('Argentina', 7, 8, 'LOCATION')]
  
  :return: A list of tuples, *(entity, start, end, label)*
docstr_tok: ["Get","NER","tags",".","Example",":",":","given","sentence","'Lionel","Messi","is","a","football","player","from","Argentina",".","'",">",">","[","(","'Lionel","Messi","'",",","0",",","2",",","'PERSON","'",")",",","(","'Argentina","'",",","7",",","8",",","'LOCATION","'",")","]",":","return",":","A","list","of","tuples",",","*","(","entity",",","start",",","end",",","label",")","*"]
code: def ner(self):
      """
      Get NER tags.
  
      Example::
  
          given sentence 'Lionel Messi is a football player from Argentina.'
  
          >>[('Lionel Messi', 0, 2, 'PERSON'),
             ('Argentina', 7, 8, 'LOCATION')]
  
      :return: A list of tuples, *(entity, start, end, label)*
  
      """
      if not self._ner_tags:
          self._ner_tags = self.text_processor.get_ner(
              self.words, return_char_idx=False
          )
  
      return self._ner_tags
  
imports: from .field import Field
  from ....common.utils.list_op import *
  from ....common.preprocess.en_processor import EnProcessor
  from ....common.settings import ORIGIN, TASK_MASK, MODIFIED_MASK
label_desc: Use image node_id 23 for calling the TextField obj's underlying member method code with example usage: obj.ner() and returns: self